The use of polyester polyols in the manufacture of PUR and PUR/PIR foams is well known. For example, see U.S. Pat. Nos. 3,892,796; 4,346,229; 4,720,571; 4,758,602; and 4,897,429 (each of the foregoing patents are now assigned to the assignee of the instant invention) and U.S. Pat. Nos. 4,608,432 and 4,609,513 assigned to Stepan Company of Northfield, Ill.
In U.S. Pat. No. 3,892,796, the residue from a dimethyl terephthalate (DMT) process is hydrogenated, and thereafter the hydrogenated residue is reacted with alcoholic materials to form fluid polyols useful in the production of polyurethane end products.
In U.S. Pat. No. 4,346,229, DMT process residue is reacted with an excess of dipropylene glycol to yield a normally liquid aromatic polyester polyol. The resulting polyester polyol is compatible with FREON.RTM. 11 blowing agent and with glycerol and can be used in the production of blown polyurethane and polyisocyanurate-polyurethane foams.
In U.S. Pat. No. 4,608,432, self-compatiblizing polyester polyols are prepared by reacting a polyalkylene terephthalate, a low molecular weight aliphatic diol, and a compatibilizer compound selected from hydrophobic compounds and nonionic surfactant compounds. The hydrophobic compound may be a fat or an oil such a tall oil.
In U.S. Pat. No. 4,609,513, a binder used in the preparation of a synthetic board made from cellulosic and/or lignocellulosic material is disclosed. The binder comprises a polyisocyanate and a mixture of reactive hydrogen-containing compounds selected from a number of specified components or mixtures of components, e.g., a mixture of polyester polyol, diethylene glycol and tall oil. The urethane modified polyisocyanurate foam board is prepared by reacting a mixture of a polyisocyanate, a blowing agent, a urethane catalyst, a trimerization catalyst, and a mixture of polyester polyols.
In U.S. Pat. No. 4,644,048, polyester polyols are made from the reaction product of a phthalic acid compound, a low molecular weight diol compound, a hydrophobic compound and a nonionic surfactant compound. These polyols are produced by a simple heating process. These polyols are blendable with various conventional polyols and other additives to make prepolymer blends that can be catalytically reacted with organic isocyanates to produce cellular polyurethanes and polyurethane/polyisocyanurates.
In U.S. Pat. No. 4,720,571, a polyester polyol is prepared by reacting a mixture comprising scrap polyethylene terephthalate, DMT process residue, and at least two glycols having a molecular weight higher than ethylene glycol in the presence of an esterification/transesterification catalyst and at a specified ratio of glycol to scrap PET and DMT process residue, and subsequently removing glycol from the reaction product.
In U.S. Pat. No. 4,758,602, polyester polyols are prepared by esterifying tall oil with an excess of aromatic polyester polyols.
In U.S. Pat. No. 4,897,429, polyester polyols are prepared by esterifying tall oil fatty acid with DMT process residue and polyhydric alcohols; that reaction product reaction is then reacted with alkylene carbonate.
The polyols discussed above have a significant drawback in that they have low acid functionality (typically an acid functionality of 1) and low equivalent weight. There is a need for polyols which have low viscosities, high equivalent weights, improved fluorocarbon solubility, and higher functionality. Polyols with these qualities will yield foams with a tough, well-cured skin, as well as, good dimensional stability, flammability characteristics and compressive properties which make them useful in place of existing commercial materials.
In this specification, the term "urethane-modified polyisocyanurate foams" refers to foams prepared from polymers containing both urethane linkages and isocyanurate rings.